Clinical Review Abstract
Trials in Progress Abstract
Abstracts selected for publication but not presentation at the Annual Meeting
Abstracts granted an exception in accordance with ASCO's Conflict of Interest Policy
A randomized phase II clinical trial of enzalutamide in combination with the therapeutic cancer vaccine, PSA tricom, in metastatic, castration resistant prostate cancer.
Genitourinary (Prostate) Cancer
2013 ASCO Annual Meeting
J Clin Oncol 31, 2013 (suppl; abstr TPS5104)
Author(s): Nishith K. Singh, Joseph W. Kim, Christopher Ryan Heery, William L. Dahut, Anna Couvillon, Myrna Rauckhorst, Sheri McMahon, Jeffrey Schlom, Tito Fojo, Philip M. Arlen, James L. Gulley, Ravi Amrit Madan; Laboratory of Tumor Immunology and Biology, Medical Oncology Branch, National Cancer Institute, Bethesda, MD; Medical Oncology Branch, National Cancer Institute, Bethesda, MD; Medical Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD; National Cancer Institute, Bethesda, MD; Laboratory of Tumor Immunology and Biology, Center for Cancer Research, Bethesda, MD
Background: There is a strong rationale to combine therapeutic cancer vaccines with hormonal abrogation in prostate cancer. Androgen abrogation augments T-cell trafficking to prostate, decreases immune tolerance, increases production of naïve thymic T-cells, enhances cytotoxic T-cell repertoire. PSA TRICOM (PROSTVAC) is a therapeutic, viral-vector based, off-the-shelf, cancer vaccine of PSA & 3 co-stimulatory molecules in phase III testing. This was developed at the NCI in collaboration with Bavarian Nordic Immunotherapeutics. It has demonstrated safety and survival benefit in a randomized phase 2 trial of metastatic castrate resistant prostate cancer (mCRPC). Enzalutamide is a modern androgen receptor inhibitor (ARI) approved for the treatment of mCRPC. Data from the clinical trials with these therapies suggest good individual tolerability without any overlapping toxicities. Analysis of previous trials suggests that vaccines may enhance clinical outcomes with ARI. These data form the scientific basis for a combination approach of a cancer vaccine with ARI to control tumor progression in mCRPC. Methods: A randomized, phase 2, open-label clinical trial at the NCI will enroll 72 chemo-naïve, minimally symptomatic patients with mCRPC. They will be randomized (1:1) to enzalutamide (160 mg daily) alone, or enzalutamide with PSA TRICOM for treatment until radiographic progression. PSA-TRICOM will be administered in a core phase (with day 1, 15 and 29 then 4 additional monthly boosts) followed by continued boosts every 3 months. The primary end point will evaluate time to progression in each arm with secondary endpoints including overall survival and systemic immune responses (lymphocyte subsets, regulatory T-cells, regulatory T-cell function, cytokines, naïve thymic emigrants). If a therapeutic cancer vaccine can enhance the clinical efficacy of a hormonal agent such as enzalutamide, it may help define a new role for vaccines as an adjuvant to standard therapies. We will also evaluate this combination in a second trial in non-metastatic, castration-sensitive patients where this combination may yield its greatest clinical impact.
Other Abstracts in this Sub-Category:
1. Clinical outcomes in patients with castrate-refractory prostate cancer (CRPC) metastatic to bone randomized in the factorial TRAPEZE trial to docetaxel (D) with strontium-89 (Sr89), zoledronic acid (ZA), neither, or both (ISRCTN 12808747).